Method of conducting combustion.



H. L. DOHERTY.

METHOD OF CONDUCTING COMBUSHON APPLICATION man NOV. 15, 1911.

1 1 87,05 1 .laflntcd J 11110 13, 19M.

Jnv mica 953% Clifouuzq I HENRY L. DOHERTY OF NEWYORK, N. Y.

METHOD OF CONDUCTING COMBUSTION.

Specification of Letters Patent. Patented June 13, 1916,

Application filed November 15, 1911. Serial No. 660,458.

T 0 all whom it may concern:

Be it known that I, HENRY L. DOHERTY, a citizen of the United States, and a resident of New York city, in the county of New York and State of New York, have invented certain new and useful Improvements in Methods of Conducting Combustion, of which the following is a specifi cation.

This invention relates to a method of-conducting combustion.

The object of my invention is to furnish a method of conducting combustion, applicable either to furnaces or gas producers, whereby. I am able to secure absolutely automatic stoking and to maintain the fuel bed free from clinker and in such an open condition as will permit the free and unobstructed passage of the draft current.

Briefly stated, my invention consists in feeding the fuel into the furnace through a comparatively high vertical or inclined (preferably vertical) feed chute, through and past a combustion zone wherein such fuel undergoes combustion, withdrawing the material from the combustion zone at a rate faster than the rate of combustion therein, cooling the said material by a current of cool gas which is advantageously secured by withdrawing through the feeding chute in contact with the cold fuel a portion of the gases from the combustion zone or region toheat said fuel and cool said g'ases, introducing the said cooled gases into the cooler part of the furnace beyond said zone and passing them up in contact with the hot mixture of fuel and ash Withdrawn from the combustion region to cool said mixture and "heat said gases, returning said gases to said zone, screening the cooled material withdrawn from the cooler part of the furnace, returning the over-screen portion of the said material to the top of the feed chute of the furnace, and feeding it back to the furnace together with fresh fuel.

It is to be noted that the combustion of the fuel in the combustion zone proper may be carried out with the production of either gases of complete combustion or the production of combustible gases similar to ordi-.

nary producer gas. This latter specific modification of the broad invention, herein claimed, I disclose and claim in my application Ser. No. 660449,,filed of even date with this application. The claims of this present application are directed to the broad invention and to ,the specific ease of carrying out the combustion to produce gases of complete combustion In the accompanying drawings I have shown a form of apparatus suit ileiie for car'- ryingout'my invention.

Figure 1 is a vertical section th ough the furnace, showing also the blower screening device and elevators. Fig. 2 is a part section on the same plane showing the grate revolved into such a position that the fuel is free to assume its natural angle of repose in chamber 1 on both sides of the same.

1 is the combustion chamber of the furnace, 2 the feed chute, 3' the cooler or ash pit, 4 the grate, 5 a fuel discharging device,

6 a grizzly or other screening device for separating the fines from the material discharged.

7 is a hopper for the return of the overscreen portion of the material withdrawn at the bottom of the furnace.

8 is a feed hopper for fresh coal.

9 iseither a steam jet or mechanical blower for creating a forced draft in the furnace.

10 is the inlet space below the grate 4 for the introduction .of primary current when the latter is set for direct firing.

11 is the space above the fuel bed formed between the surface of the fuel and the walls of the chamber.

12 is the gas flue which conducts the hot combustion gases from the furnace to the fines of a boiler or other apparatus in which they are utilized for heating.

13 is an elevator for raising the overscreen portion of the material withdrawn at the'bottom of the furnace to the hopper 7.

14 is a coal conveyer which supplies the fresh fuel to the hopper 8.

15 is the gas ofi-take at thetop of fee chute 2.

1G is a mechanical or jet blower draws olf a portion of the furnace gases through 15 and forces them through the pipe 17 into the lower part of the fuel cooler 3.

18 is the space left between the end of the g .e 4 (when the latter is in use) and the which. 106

pose of the fuel, any thickness of fuel nayjg igr part of the furnace.

be maintained between the primary current inlet space 10 and the-gas off-take space 11 up to the limitations of the apparatus. In this position of the grate the apparatus may be operated the same as an ordinary gas producer, except for the fact that the direction of flow of the draft current will be laterally across the fuel bed instead of in a vertical direction through the same.

Assuming that the grate is set in the position shown in Fig. 1, the method of operating the apparatus to carry out my invention would be as follows: Either fuel or coarse cinder is charged into the top of the fuel chute 2 and permitted to fall over the grate and into the cooler 3 occupying the lower This material is charged until the mass in the cooler 3 is built up to the space 18 left between the end of the grate and the wall of'the furnace. Kindling is now charged onto the grate 4 through 2, and ignited. More coal is now introduced through 2 until a bed of ignited coal has been built up on the grate *4. As this latter is set either on or'slightly below the angle of repose of the material, the coal as it is charged tends to build up against the wall of the furnace at the space 18 and then on its natural angle of repose over the face of the grate until it has filled up to the bottom of the chute 2. The coal may now be rapidly charged into the, hute 2 until the latter is full. The air for supporting combustion I enters the furnace through the dampered air inlet 19, passes into the space 10 below the grate, thence through the inter stices of the grate into the ignited fuel thereon, the oxygen of the air uniting with a portion of the carbon of the fuel, the resu ting gases discharging from the fuel bed into the gas space 11 above the same. From 11 the combustion gases pass through the fine 12 into the boiler or other heating ap paratus in which it is intended to be used. By means of the steam blower 9 the furnace may be operated under forced draft the Same as an ordinary boiler furnace. Instead. of 9, a mechanical blower of any type desired may be used. The apparatus is now in shape to be put in normal operating condition. Either continuously or intermittently part of the mass occupying chamber 3 is withdrawn through the discharging apparatus 5. The material discharged through' bottom the proper proportion of fresh coal which is required to be mixed with the coked fuel to maintain the supply to thecombus.

tion chamber 1 at the normal point is introduced through the hopper S. The coal is fed continuously into 8, or intermittently as may be desired, by means of the coal conveyer 14, or any other preferred type of conveyer. The conveyer shown comprises a traveling chain of linked buckets which runs over the fuel hopper 8 and under the ash hopper 21. The conveyer is advantageously of the tipbucket type in which the buckets can be discharged at any desired place on their path of travel by setting a tripping device provided for that pungose. As material is withdrawn at the bottom, the fuel mixture falls by gravity from the chute 2 onto the grate 4. In passing over 4 more or less of the fuel is burned, according to the rate at which the fuel mass is withdrawn through 5 and the velocity and volume of the draft.

In regulating the rate of withdrawal of the fuel from 3, and consequently the rate of feed of the fuel onto the grate or into the combustion chamber 1, when the grate is not used, two considerations must be borne in mind. In the first place, it is necessary to draw the material from the bottom of the furnace at a rate such that sufiicient coked fuel will be available to secure the proper proportioning of the fuel mixture fed to the furnace, with regard to the oaking character of the fresh fuel. If this latter possesses marked caking qualities a larger proportion of coked fuel is required in the mixture to prevent the formation of pasty aggregates by the fragments of the fresh coal than is necessary with hard fuel or a fuel intermediate between the two. Nearly all coals, even the impurer grades of anthracite, will soften more or less when first exposed to high temperatures. In the case of true coking coals, there is apparently an actual semi-fusion of the coal itself, the pasty lumps uniting at their surfaces of contact to form coke aggregates in the well known manner. In the case of ordinary soft coals, no true coke is formed, but, when the fuel is firstheated, it becomes more or less softened and, in the presence of a considerable proportion of ash, becomes entangled with the pasty ash particles in the clinker. In the case of the smaller sizes of anthracite, which nearly always contain large proportion of mineral, or ash-for1ning matter, of com 'iaratively easy .fusibility, it is seldom that the material rejected from the grate contains less than 50% of combustible matter. This is due to the formation of clinkcrs by the ash and a portion of the unburned fuel. The masses of coke or clinker thus formed act to impede and, in some cases, to practically shut off the draft through thefuel bed. This action I largely prevent by my invention, by mixing with the raw fuel a, suitable proportion of preformed. coke. Coke requires a temperature nnich above that of its formation to cause it to again soften. By using a suitable proportion of coke in the fuel mixture therefore, I. to a large extent, separate the coal particles from each other so that when they are softened by heat they are prevented from coming into contact and so forming aggregates. in the second place, sufficient unburned fuel should be maintained on the grate l. or in the chamber 1, to keep the ash residue from the portion of the fuelburned down to a comparatively small roportion of the mixture. Even, there ore, when sufficient coked fuel can be obtained by a moderate rate of drawing to satisfy the first requirement, it is sometimes necesi sary to increase the rate in older to provide the necessary coked fuel to satisfy this second requirement. By thus keeping the proportion of free ash in the fuel bed in the combustion region comparatively low I am able to pretent the formation of clinkers, since the large proportion of unburned and voiced. fuel in the ma s prevents the union of the nasty ash particles to form clinkers. the same manner the coke in the fuel bed Herr to separate and prevent the agglomeration of the coal fragments which have been softened and rendered pasty by the heat. lVith easily fusible ash it is advantageous to so regulate the speed of advance of the fuel column that the proportion of free.

ash in the mixture of ash and unburned fuel in 3 will not exceed 5% of the total weight of the mixture. W'ith other fuels Whose ash more infusiblc the rate of advance of the fuel maybe regulated to that which will produce a mixture having as "much as 20% offree ash in 3 without causing any seri-' ous retardation. of the draft. Usually, however, the fuel column should be advanced at a rate that will prevent an increase in the proportion of free ash in the mixture in the cooler above 10% of the mixture. Itis obvious that by using a sulliciently rapid of advance of the fuel column and a 1 proportion of coarse coke or carwnizell file-l. in the initial fuel mixture, I nnzinta'in the fuel. column. in a condition will maintain good proportion of "v ids in the mass. thus insuring the maintenance of a comparatively free and mobs-ten ted passage for the draft current. ly thus always maintaining a comparati ely large proportion of unburned and coiled fuel on the grate for in the chamber 1 and in the chamber 3, I. am able to mainiin fuel bed in an open condition afailing free passage to the draft current 3: through it.

r normal operation, by means of the blower 16 (which is preferably of a inechanical type, although steam jet similar to that shown at 9 may be substituted for the mechanical device) a portion of the gases produced in furnace chamber 1 is drawn up through feed chute 2 in contact with the fresh fuel filling the same, down through the pipe 15. and forced through pipe 17 into the bottom of the cooler 3. Owing to its being brought into contact with the cold fuel in passing through chute 2 the initially hot gases from chamber 1 are cooled down to a ten'iperature below that of ignition of the fuel. At the same time, the fuel in the lower part of chute is heated up to the temperature 'of carbonization and most of the volatile constituents of the fuel are distilled' passes through the passage 15, blower 16 and passage 17, as already stated, .into the lower part of cooler Passing up through cooler 3 this cold gas is brought into contact with the hot material which has passed over the grate, and which is, of course, initially at a high temperature on its entrance into 3, and takes up the heat from this discharged fuel and is itself heated nearly to the temperature at which the'fuel passes through the space 18. If the gases passing up through cooler 3 contain any considerable amount of gases which react with incandescent carbon g. carbon dioxid, Water vapor or hydrocarbon gases) more or less of such gases will undergo reduction in contact with the incandescent carbonized fuel in the upper part of 3, generating combustible gas. When my invention is being used for the so-called direct firing of a boiler or-other heating apparatus the gases discharging from the fuel mass on grate 4 will contain more or 1235 free oxygen. This is due to the fact that In order to secure a sufliciently rapid combustion of the solid fuel on 4 it is necessary to supply to the fuel. an amount of air in excess of that carrying the quantity. of oxygen with which the fuel can react. In other words, it. is necessary to maintain a considerable proportion of free oxygen in the atmosphere in contact with the fuel in order to secure a reasonablyrapid combus tion. To insure such an excess of oxygen it is therefore necessary to add to the com' Nov. 15th, 1911'.

would be a greater volume of gas to be heated by the combustion. By my invention I correct this necessary result of the so-called direct firing by the combustion which takes place between the combustible containing gas ascending from the cooler 3 and the excess oxygen mentioned. The combustible constituents in the gases from the cooler 3 are burned, either wholly or in part, according to the proportion of free oxygen present. Indeed, in this embodiment of my invention, it is advantageous to supply to the fuel on grate 4 a sufficient volume of air to insure the presence in the gases discharging from the fuel on the grate 4, of. a sufficient proportion of free oxygen to burn the combustible constituents of the gases passing into furnace chamber 1 from the cooler 3.

By this feature of my invention and the proper regulation of the rate of advance of the fuel over grate 4, therefore, I am able to burn the solid fuel on the grate 4 under conditions which are favorable to a very rapid combustion of the fuel, since I am able to pass through the fuel mass a relatively large volume of air so well-distributed that practically every particle of the fuel is surrounded with an atmosphere containing free oxygen without the necessity of having any considerable quantity of free oxygen in the passing to the heathot combustion gases utilizing apparatus. The combustion gases discharging from the chamber 11 can thus be maintained at the highest practicable temperature. Since the speed of heating (in a boiler, for example) depends largely upon the temperature difference maintained between the heating gases and the heat receiving material the utility and importance of this result of my invention is obvious.

When using the second embodiment of my invention in which the fuel is burned in a' thick bed to form principally carbon monoxid, the gas drawn up through the fuel in the feed chute 2 is, of course, What is technically known as producergas. To this is added the distillation gases derived from the volatile matter of the fuel. When this gas mixture is passed u through the fuel in the cooler 3, there Wil be but little reaction with the fuel in this case, but the sensible heat of the fuel in excess of the temperature at which the gas is introduced into cooler 3 will be taken up by the gas current and the gases will enter the space 11 and mingle with the .main stream of gas generated in 1. This modification of my invention I do not claim specifically herein, it forming the matter claimed in my divisional application Ser. No. 660449,-filed This method of making combustible gas is only claimed herein in its generic relation to the broad invention.

During ordinary operation I aim to draw oil through 15 and introduce into the cooler the draft diflicult.

to install a mechanicallystoked plant.

3 in the manner described a suflicient volume of cold gas to cool the fuel discharged from the combustion chamber down to approximately the temperature of the gas introduced by the time the fuel and ash mixture has reached the discharging apparatus 5. By this device I am able to withdraw from the combustion chamber a suflicient proportion of coked coal to largely prevent clinkering even when using highly caking coals. without incurring any loss of heat by so doing. Owing to this fact, I am able to force through the furnace a-much greater volume of draft than is possible in ordinary firing and so can work with a much thicker bed of fuel on the grate 4 and still obtain a completely burned eflluent gas. As is well known, in ordinary boiler firingit is not possible to maintain a thickness of more than about 6 inches of fuel and ash on the grates without seriously retarding the passage of the draft. This is due to the action of the coal under high temperatures mentioned whereby it assumes a soft pasty condition which tends to form the fuel into aggregates or cake, thereby closing up the interstices of the fuel and making the passage of I am thus able to secure a much greater rate of combustion of the fuel per square foot of grate surface (or er square foot of cross-section of the fuel ed) than is possible either in direct-fired furnaces or producers operated in the ordinary manner.

- When the furnace is operated with the grate shown in the position of Fig. 2 there IS no material difference from the method of operation already dscribed, except that the form of combustion in the furnace 1 is now changed to the imperfect combustion of car- 105 bon to carbon monoxid, such as occurs in the ordinary gas producer. In this case the gas discharging through the fiue'12 has, 'of course, more or less of the character of producer as and now requires an additional 110 supply 0 air in order to effect complete combustion. In this case the gas can be conducted to a furnace situa id at a distance and there burned the same as ordinary producer gas.

From the above description it is obyious that with my method of conducting combustion the stoking of the fuel bed is entirely automatic, the movement of the fuel through the furnace being accomplished entirely by 120 gravity and not requiring any mechanical power-operated stoking device. The advantage of this will be very apparent to those skilled in the art, since it is well known that mechanical stokers are subject to great wear 126 and are very liable to get out of. order. Besides this, the initial cost is' high, and I can erect a furnace to operate under mysystem at a much less outlay than is required As before stated, my invention may be used with either intermittent or continuous operation without affecting the principles of operation on which my invention is based' It is to be noted that in diverting a portion of the combustion gases from chamber I through the fuel chute 2- I do not thereby sacrilicc any of the heat generated in the combustion chamber 1, since in passing through the cold fuel practically all the sensible heat which the gases initially hold is given up to the fresh fuel which is passed to the grate. Indeed, this preheating of the fuel is a very decided advantage since it enables me to bring the fuel onto the grate 4 at a temperature approximating that which is normally established in the fuel on 4 by the combustion. There is thus no momentary chilling of the furnace such as occurs when charging the ordinary direct fired boiler furnace.

By my invention I am able to secure much more uniform firing of a boiler or other appz-iratus than is at all possible by means ofthe ordinary direct fired furnace. Besides this, the free passage which is always open to the draft current through the fuel bed on grate l or in chamber 1 makes it possible to maintain a. practically constant draft through the furnace and heat utilizing chamber which is not possible in the ordinary manner of firing. In ordinary firing the fuel bed is constantly varying in regard to the proportion of interstices which it contains and for this reason. the back pressure on the draft current is constantly varied. In order to maintain a constant volume of draft, therefore, in this case it is necessary to be constantly varying the discharge of steam through the blower 9, or the speed of the mechanical blower when such is substituted for 9. in order to force a constant vplume of air through the grate. Since such constant attention to the draft is impracticable in ordinary firing, the result is that the volume of draft is constantly varied. This, in turn, produces a constantly varying steam generating effect in the boiler itself. In plants where the rate of steam generation is designed to closely approximate the rate of steam consumption, in order to maintain a uniform pressure for the engine it is absolutely necessary to provide steam drums of large capacity so that the fluctuation in steam generation may be, so to speak. governed by ha ving a large reservoir of steam upon hich the engines may draw during periods of low steam generation. By my method of operation, on the contrary, it is possible. where the load is practically uniform, to operate with very small steam drums. The advantage of this regular and uniform firing which I am able to secure by applying my method of p ration to furnaces is of equal advantage when the apparatus heated is an ordinary furnace as when it is used for heating a boiler. Indeed, in many metallurgical operations the maintenance of uniform firing is of more importance than in boiler operation. My invention, therefore, is peculiarly well adapted for firing such furnaces.

While I have described above the method of operation which I deem the most advan tageous, it is to be understood that modifications may be made in the details of operation without departing from my essential process. For example, instead of using cold combustion gas alone to cool the fuel and ash in the cooler 3, I may use a mixture of combustion gas and steam, or steam alone. ()r I may, instead of using the hot gases from the furnace itself to preheat the cold fuel, use hot waste combustion gases from a metallurgical furnace where such are available. If the preheating of the fuel is not deemed necessary, this operation may also be dispensed with.

The main and indispensable features of my invention I consider to be the passing of the fuel through the combustion chamber at a rate greater than that of combustion in the chamber, the cooling of the material discharged from the chamber-and the return of coked and unburned fuel in the material to the combustion chamber in admixture with fresh fuel.

1e application of this invention to the operation of a gas producer I do not specifically claim herein. this forming the matter of another application.

The method of heatrecuperation by restoring the heat of material advancing beyond a zone of combustion to the material in the combustion zone and to the material advancing to said zone by utilizing a gaseous current as the medium of transfer, I do not claim broadly herein, that forming partof the matterof my prior and co-pending application Ser. No. 535,841, filed Dec. 31st, 1909. Nor do I claim broadly herein this method of heat recuperation as applied to the coking and distillation of coal where such combustion is a mere incident to said coking and where distillation gases are re covered for use elsewhere, this being part of the ,matter of co-pending applications.

Having described my invention, what I claim is:

1. The method of conducting combustion which comprises, advancing a column of fuel through a relatively long conduit having an intermediate localized combustion zone, withdrawing from said combustion zone a portion of the combustion gases formed therein, passing the said ortion of combustion gases in contact with the portion of said fuel column advancing toward said combustion zone to reheat the fuel in said portion of said co umn and to cool said gases, con .ncting the cooled and non-combustion-supporting gases to the portion of said fuel column advancing through said conduit beyond said combustion zone. and contacting said cooled gases with the material in the said column beyond said combustion zone. to cool the said material and to heat said gases.

2. The method of conducting combustion which comprises. advancing a column of fuel through a relatively long conduit having an intermediate localized combustion zone, uithdrawing from said combustion zone a portion of the combustion gases formed therein. said combustion gases being of non-coinbustion-supporting character. passing the said portion of combustion gases in contact with the portion of said fuel column advancing toward said combustion zone to preheat the fuel in said portion of saio column and to cool said gases, conducting the cooled noncombustion-supporting gases to the portion of said fuel column advancing through said 0011-, duit beyond said combustion zone. and contacting said cooled non-combustion-slipporting gases with the material in the said col umn beyond said combustion zone. the volume of said portion of cooled combustion gases being that which will suffice to cool the material in the portion of the said fuel column beyond said combustion zone to the desired degree.

3. The method of conducting combustion which comprises. advancing a column of fuel through a relatively long conduit havin; an intermediate combustion zone. at a rate greater than the rate of combustion of said fuel in said zone. and quenching unconsumed material in that portion of said column bayou-l said combustion zone by contacting with said material a stream of a relatively cool gas containing less free oxygen than that required to maintain the combustion of the combustible matter in said material. to cool said material and to heat the said gas stream. and passing the soheated gas in contact with the fuel in that portion of said fuel column in said combustion z ne.

4-. The method of conducting combustion which comprises, feeding fuel through a combustion zone at a rate greater than the rate of combustion of said fuel therein. the rate of feed of said fuel being that required to insure a suflicient proportion of unburned fuel in the mixture of fuel and ash discharged from said. combustion zone to maintain said mixture in a condition easily permeable by the draft current, removing anburned fuel and ash from. said zone. and returning to the said combustion zone heat carried out of said zone by the unburned fuel and by the ash of said burned fuel. by conducting cool non-combustion-supporting gas through said mixture and into said combustion zone.

5. The method of conducting combustion which comprises, feeding fuel through a combustion zone by gravity at a rate greater than the rate of combustion of said fuel therein. the rate of feed of said fuel being that required to insure a suflicient proportion of unburned fuel in the mixture of fuel and ash discharged from said combustion zone to maintain said mixture in a condi tion easily permeable by the draft current, removing unburned fuel and ash from said zoneband returning to the said combustion zone heat carried out of said zone by the unburned fuel and by the ash of the burned fuel. by conducting cool non-combustionsupporting gas through said mixture and into said combustion zone.

ll. The method of conducting combust on which comprises. feeding fuel through a combustion zone at a rate greater than the rate of combustion of said fuel tlu rein. therate of feed of said fuel being that required to insure a sufficient proportion of unburned fuel in the mixture of fuel and ash (ii-- charged from said combustion zone to maintain said mixture in a condition easily per mcable by the draft current. removing unburned fuel and ash from said zone, and returning to the said combustion zone heat carried out of said zone by the unburned fuel and by the ash of the burned fuel by first contacting a non-combustion supporting gas with the. unburned fuel and ash and then introducing the said gas into the fuel in said zone.

7. The method of conducting combustion which comprises feeding fuel through a combustion zone all a rate greater than the rate of combustion of said fuel therein, the late of feed of said fuel being that required to insure a sufficient proportion of unburned fuel in the mixture of fuel and ash discharged from said combustion zone to maintain said mixture in a condition easily per meable by the draft current, removing unburned fuel and ash from said zone. contacting with the unburned fuel and the ash of the burned fuel a stream of an initially cool non-combustion-supporting gas to cool said unburned fuel and ash and to heat the said gas. and conducting the said heated non-combustion-supporting gas into the said combustion zone.

8. The method of conducting combustion which comprises. feeding fuel through :1 combustion zone at a rate greater than he rate of combustion of said fuel therein. lilo rate of feed of said fuel being that re quired to insure a sufficient proporti n" of unburned fuel in the mixture of fuel and ash discharged from said combustion zone to maintain said mixture in a condition ens iljv i-l "meuhlc by tlw draft curruui. remuw 511;! llllHllllLil fuel :Hlll ash from mid 720K191, mntiu-ling uiih thv unburned fuel and the ash 01' th hurnwl fuel :2, stream of an initially 1- 0l nuu-umnhuui'm-supporiinp; 213 to c l haul nmllurials an! to h ui suid ('(Hilllhtifljlf the mu heui i'l gas into ihi- Slllll munhusiiuu mm :nul m ngling uMmAm-u wl gas niih the draft (llllllli passing through Sillll iimnluistiun :mnu, wh m-win heat (:Hl'ltfl out (if suiil imnhustiun mnv hr ilu- Sillll llllllkl'lfllf rviuiuml to riz iil 910M0- l). The mvthml (-1" ('mnluviing umulaustiun which C(Pll'llillfii'h. hauling: flu-l through i-nmhustion 2011i in gravity at u rate grvutvr than the rate ui" uuuhuuim: n" hikill fuel. therein. the rate of lM-il of will furl living that rcquirml in i. um :i sufficient prngmr tion of unlmrnml fuul in ihv m'xiuw of fuel and ash lll-ulllligffl from said vmnhusiiwn znne tn muin-tuin mid mixl'uiwr in u (:mulitinn easily pvrinunhh) by the ill'ufi/ current, removing unhurnvd fuel uml us'h from ui i zone, and riuurnizzg m ilu will CuillbHHtiUll min?- the major rum u'f {1m hull curried out f Said zone by hr uuhu nwi ml and in the ash of the blll'nfll fun! by (Hil?;i(l2l; f ith the hot uuluu'nwi w'uvi =1 ml uuh :1 winiiisl (r001 non-(mnhuuii in-supporting gas to hunt said gas; mui p: ing' he snJuuizml ,u'us; imm szii jl COllliJllFilUU 21mm i The meth ui' hinting mmhuu whisk rump 19%,, fv-wlinyr fu-l n 21m liHL' l 'Zi'i winhuxiion 70MB :it 21 rule J'mi'u' t i=1; flu min ml vismimstiuu (if said hurl u u-in! :lua rule n! veil F i *l uvl living that .i'ctluircd in insur" u s'uiiivivn'r uwpnrfiuu n" ui'iluu'uawl haul n the ruiztau'v of f twl and 11: lil l irtll i i 1. mun buslim: 1101M in nnuumiu illil u'uxiurw in :1. (Ohiilfiflil vrmily iu-rimulne ha ilw \irui't current. rvmuiiug: uuhuiumi 'uvl uml ash from said :cmun nuuusijmg will flu iliil llllbll 'lli' l fuel and ash f" ilull'l'ill'li fuvl u utrvzun ml" an iuiiirll 7WEi- 'i ll1lll,- tinn sumuu'tmg gr I v w Hr! iui'iuh :Hl-i w limit liqmm in h' ill limb pfus lul liu wi Mimi zm'un l minu'lu 1hlii (131m thev (huff. UHI'INHI. i ihl'irllflll F-uh'l ('unihustiun Zuni wlu-ir-lgi' Jll nzrrimi nut of said combustion miw by iizc said mutei'ials is returned to Qui l zone.

11, Th? method 0* windsurfing manhustiun which ('umprisas. fuelling fuel lhmugh 21 combustion zone at 1: mite greater than the rate of cnml'iustimz of xiii-fl fuel ibluirhin the rate of feed of said fuel being that required to insure a sufficient prupurtion of unburned fuel in the mixture m fuel. and ash discharged from said cim'zhus l'iun mm: to main tain said mixture in 8 condition ausilv permeable by tin draft r'urrmt. removing}; uiuburned fuel and ash fra'm, said who. r4:-

iv: (if H turning: to the said con'ihustiim mum hem :arrieil nut. of said mm h rho uui uziwi fuel and the ash of the burned ating the said unhurnad fuel rum usln and: returning he (1" nnluzrnm! ui in said ((iinlJHSiiOH mm? m aaiiuixium uni; l'rwh fuel.

1:). Tim method uf cnmiuvl'iug vmnluu tiun whivh i-(nnpriM-s. lmuiing; luvi w un through :i mnihustim'i zone at ti jiiil" blikllPI' than the nihufe'mnhu lionnfsuul flu in ill! run) of evil uf suld fuel Ewing iii-n q irwl in inuurv u sul'liclenl 'unguu'tiwn uuluuniu fuel in the mixiure f 1292 ml; l ilf-ll2ll'jlll frum said munliu' to uuiinmiu will mixrure in :i emulil u ma il uu'nwuhhby the drui't nu; mm we in; lfll lllillwll fiu-l and Hall E'rmu r-untm-ling Willi the mid 1H: mrnwl 1" urri l Hi the burned fuel a fitrmn'u 1:? mi tizilly cool gaseous fluid in win? flu unluunml fuel and ash uf 2hr l*il'll**-l and (0 limit suiil {.ZzusCfNu-f Hui-L thv will unburned fuvl from. u: returning un'burnwl flu-i tu will uelnwi; m ne in zulmixlurc with i'rwh imil.

11 The mPth-"ul of minim-ting wmlvri .lllfil. vompriw funding: i'uvl l,i'i\ll mmlmstinn zunv at rate g n-Him iiium if rate of mn'iliustion 0f sziiii fuel alumni, l rule of fQQll (if said fur-l liv n that lE l i Iih) insuw u suflivivnf prnpuriiun of uulu.

m mil vmnliuniun zone by th? said mntvriuls is rvturuwl Kn Raid znne. separating the $Hl'll uuhuru-m mull-rial from said ash and r6. lurningg wpurnreil unburned material in mid (-umhusiiun zone in admixture with frwh fuel.

14. The method of conducting UOIlilHlStinu whivh comprises, feeding fuel by gz'zn'ic v thruugh a ('omlmstiun zone at a rate greater than the PM? of vomhustinn of said fuel therein, the rate of feed of said fuel being that required to insurv a ullivivnt prupmtiui of unburnml fuel in thrmixturc 0f fuel and nshfllisvluiu rml from said (orhustiun 2mm to maintain said mixture in u ounilitiun easily perumililo li v iln' draft current; mun-ring m uu'm-rl fuvl and ash from si usl zunc. run hiding will; the said unburned fuel and nah ul thv lvurnc l fuel a stream of-un hlitiully cool gaseous fluid to cool the said materials and to heat the said gaseous fluid, conducting the said heated fluid into said combustion zone, separating the said unburned fuel from the said ash and returning the said unburned fuel to said combustion zone in admixture with fresh fuel.

15.- The method of conducting combustion which comprises,v feeding fuel by gravity through a combustion zone at a rate greater than the rate of combustion of said fuel therein, removing unburned fuel and ash therefrom, contacting with the unburned fuel and the ash of the burned fuel a stream of an initially cool gaseous fluid to cool the said materials and to heat the said gaseous fluid, conducting the heated fluid into the combustion zoneand mingling the said heated fluid with the draft current passing through said combustion zone, whereby heat carried out of said combustion zone by the said materials is returned to said zone, separating the said unburned materials from said ash and returning the said unburned material to said combustion zone in admixture with fresh fuel, the proportion of the returned fuel in the mixture being that required to substantially prevent the caking of the said fresh fuel.

16. The method of conducting combustion which comprises, feeding a mixture of fresh and carbonized fuel in regulated proportions to a combustion zone at a rate greater than the rate of combustion of said fuel therein, the rate of feed of said fuel being that required to insure a sufficient proportion of unburned fuel in the mixture of fuel and ash discharged from said combustion zone to maintain said mixture in a condition easily permeable by the draft current, burning a portion of said fuel in said combustion zone, removing unburned fuel and ash there from, separating unburned fuel from ash of the burned filel, returning the said unburned fuel to the said combustion zone in admixture with fresh fuel, withdrawing from said combustion zone a portion of the gases generated in said zone and passing said portion of gases in contact with the said mixture of.

carbonized and fresh fuel being fed to said zonerto heat the said fuel mixture prior to introducing the same into said zone to cool the said portion of said gases.

17. The method of conducting combustion which comprises. feeding a mixture of fresh and carbonized fuel by gravity to a combustion zone at a rate greater than the rate of.combustion of said fuel therein, the rate of feed of said fuel being that required to insure a sufficient proportion of unburned fuel in the mixture of fuel and ash discharged from said combustion zone to maintain said mixture in a condition easily permeable by the draft current, removing unburned fuel and free ash from said zone,

separating unburned fuel from ash of the burned fuel, returning the separated unburned but carbonized fuel to the said combustion zone in admixture with fresh fuel, withdrawing from said zone a portion of the gases generated in said zone and passing said portion of said gases in contact with the said mixture of carbonized and fresh fuel which is being fed to said zone to preheat the said fuel mixture prior to introducin the same into said zone and to cool the sald portion of gases.

18. The method of conducting combustion which comprises, feeding a mixture of fresh and carbonized fuel by gravity to a combustion zone at a rate greater than the rate of combustion of said fuel therein, burning a portion of said fuel in said zone, withdrawmg unburned but carbonized fuel and free ash therefrom, separating unburned fuel from ash of the burned fuel, returning separated unburned fuel to said combustion zone in admixture with fresh fuel, the proportion of unburned fuel in said mixture being that required to maintain the fuel bed in said combustion zone in a condition permeable by the draft current passing therethrough, and preheating the said fuel mixture prior to introducing the same into said combustion zone by assing in contact therewith a stream of initially hot gases.

19. The method of conducting combustion which comprises, preheating a body of fuel by contacting therewith a current of hot gases, feeding the preheated fuel through a combustion zone at a rate greater than the rate of combustion of said fuel therein, the

rate of feed of said fuel being that required to insure a sufficient proportion of unburned fuel in the mixture of fuel and ash discharged from said combustion zone to maintain said mixture in a condition easily permcable by the draft current, burning a portion of said fuel in said combustion zone, removing un burncd but carbonized fuel and free ash therefrom, contacting with the said unburned but carbonized fuel and free ash a stream of an initially cool gaseous fluid to cool the said materials add to heat the said gaseous fluid, conducting the said heated fluid into the said combustion zone and mingling the said heated fluid with the draft current passing through said combustion zone, whereby heat carried out of said zone by the said materials is returned to said zone.

20. The method of conducting combustion which comprises, feeding fuel through a combustion zone at a rate greater than the rate of combustion of said fuel in said zone, burning a portion of said fuel in said zone, removing unburnt but carbonized fuel and free ash from said zone, returning to the said zone heat carried out of said zone by the unburned fuel and by the ash of the burned fuel by contacting therewith a an"; fur)! ill Zone, hr

fires P r hwitha said m'uu ing zone and there contacting the said cooled gases uith the hot mixture of unburned carbonized fuel and the ash withdrawn from the said combustion zone to cool the said mixture of fuel and ash, conducting a major portion of the said combustion gases to a heat utilizing apparatus, withdrawing the cooled mixture of fuel and ash from said fuel-cooling roue, separating the unburned carbonized fuel from the said ash and mixing the separated carbonized fuel in regulated proportion with a quantity of fresh fuel to form another volume of fuel mix ture, the proportion of coked fuel in said mixture being that which will prevent the caking of the said fresh fuel.

26. The method of conducting combustion which comprises, feeding a mixture of fresh. fuel and carbonized fuel of regulated composition to a fuel conduit, advancing the said fuel mixture into a combustion zone at a rate greater than the rate of combustion of said fuel therein, burning a por tion of said fuel in said combustion zone, discharging the unburned but carbonized fuel and free ash from the burned fuel from said Combustion zone, withdrawing a minor portion of the hotgases formed by said com bustion-from said zone and passing the said minorportion contact with a volume of the mixture of fresh and carbonized fuel in said fuel conduit to preheat the said mixture and to cool the said gases. conducting the cooled gases to and. passing them in contact with the mixture of carbonized fuel and ash discharged from the said combustion zone, the volume of the gases so withdrawn from said combustion zone and contacted with the fuel in said fuel conduit in a given interval of time bein regulated to the volume required to cool the quantity of ash and carhoi'iizedr fuel discharged from the said combustion zone in a correspond mg oeriod of time.

27. he method of conducting combustion which comprises, feeding by gravity to a, fuel conduit a mixture of fresh fuel and carbonized fuel in regulated piaioortions, advancing the said mixture t a combustion zone at a rate greater than the rate of combustion of said fuel in said Zone, burning a portion of said fuel in said zone. dischargn ing the unburned but carbonized fuel and the ash residue from the burned fuel from said zone, witlulrawing a minor portion of the hot combustion gases formedby the said combustion from said zone. passing the sai-l minor portion of combustion gases in contact with another \olunie of the said mixture of fresh and carbonized fuel in said fuel conduit to preheat the said mixture and to cool the :iid port on of gases, eonductinr the cooled gases, to and passing them in con tact with the mixture of carbonized fuel and ash discharged from the said combustion zone, the, volume of the gases with drawn from d combustion zone and contacted with the fuel mixture in said conduit in a given interval of time being adjusted to the volume requir d to cool the quantity of ash and cadmium? fuel discharged from the said combustion zone in a corresponding period of tim 28, The ineiliod of conducting combustion which comprisra h uling a mixture of fresh fuel and car! will ed fuel in regulated proportions to a fuel conduit, advancing said fuel mixture into a combustion zone at a rate greater than the rate of combustion of said fuel therein.burning: a portion of said fuel in. said zone, discharging the. unburned but carbonized fuel and the ash fr m the hurned fuel from said combustion zone, withdrawing a minor portion of the hot combustion gases formed by said combustion from said zone and passing the said gases in contact with a volume of the mixture of fresh and *arbonized fuel in said fuel conduit to preheat the said mixture and to cool the said gases. conducting the cooled gases to and passing them in contact with the said mixture of carbonixed fuel and free ash discharged from said rombustion zone, the volume of the said portion of gases withdrawn from the said combustion zone and contacted with the fuel mixture in said conduit in a given interval of time being regulated to substantially the volume required to cool the. quantity of ash and carbonized fuel discharged from the said zone in the same perind of time, separating the carluinized fuel from the said ash and mixing a regulated quantity of fresh fuel with the said carbonized fuel to form another volume .of th fuel mixture for said comb stion zone, the proportion of the carbonized fuel in the said mixture being that required to maintain the fuel bed in said combustion zone in a c ndition permitting the easy passage of the draftrurreut thercthrough.

if The method of coi'ulurting combin Ulon whirl; coinprie-i-a fe ding by gravity a mixture. of fl' fsll tool and :faibonized fuel in regulated proporti ns to a fuel conduit. ad- \aiuiun; the said uiivture into a conl bustion zone at a rate greater than the rate of conr luislion of said fuel therein, burning a portion of mid fuel bi m,- zonc. withdrawing the bot nciru il but carboulie fuel and tire xi. il'ff-lll the burned fuel from said vou'ibustion zone and advancing them into a cooling zone at a rate such as. will insure the presence of suflcient unburned but carbonized fuel in said. mixture of fuel and ash in said cooling zone to render the said mixture easily permeable by the draft current, withdrawing a portion of the hot combustion gases formed in the (amibustion of said portion of the. fuel from said zone and passing the said gases in contact with a volume of the mixture of fresh and carbonized fuel advancing towardsaid zone to preheat said mixture and to cool the said gases, conducting the cooled gases to and passing them in contact with the said hot mixture of carbonized fuel and ash withdrawn from said combustion zone, the volume of the said portion of gases withdrawn from the said combustion zone in a given interval of time be ing regulated to substantially the volume required to cool the quantity of ash and can bonized fuel discharged from the said zone in the same period of. time to the desired degree, separating the carbonized fuel from the said ash and mixing, a regulated quantity of fresh fuel with the said carbonized fuel to form another volume of the fuel mixture for said combustion Zone, the proportion of carbonized fuel in the said mixture being that required to substantially prevent the obstruction of the draft through said conibustion zone by the raking (if the fresh fuel.

30. The method of conducting combustion which comprises, maintaining a body of fuel in a comparatively long conduit in such manner that the said body of fuel will be cruised to move through ,a combustion zone of said conduit as the fuel mass is removed from the lower part/of said conduit, removing material from ,t e extremity of said fuel body beyond said combustion zone and adding" fresh fuel to the portion of said fuel body in advance of said combustion zone, maintaining combustion in the middle portion of said fuel body, with the production of gases of complete combustion by supplying a regulated quantity of air to said. middle portion only of said fuel body, the volume of" air so supplied being so correlated to the rat of advance of said fuel body that av substantial proportion of said fuel will pass tho: h the said combustion zone unburned to insure the presence of sulli- (lent unburnedl'i: .l mixed with the ash in the portion of said fuel body beyond said combustion tone, to keep the material in the said portion of said fuel body in a condition permitting easy penetration of said portion of said fuel body by a combustionquenching fiuith passion sutlieient of said combustion-qucm-hing fluid through tli said portion of said fuel body to extinguish the said ignited unburned fuel therein. and withdrawing the material from the said portion of said fuel body in a quenched and comparatively cool condition.

31. The method or conducting combustion which comprises, maintaining a body of fuel in a furnare zone in such manner that the said body of fuel will be caused to move through said zone: as the fuel mass is removed from the lower part of said zone, re-

moving material from the bottom of said body of fuel and charging fresh fuel onto the top of said body of fuel, maintaining combustion in the middle portion of said body of fuel by supplying air to said middle ortion, the volume of air so supplied being such that a substantial proportion of the fuel entering said combustion zone will pass through the same unconsumed, and contacting with the residual mixture of carlnin ized fuel and ash that has passed through the said middle portion of said body of fuel a stream of initially cool non-combustion supporting gas; the volume of the said gas relative to the speed of advance of the said residual mixture being that required quench the unburned fuel in the said mitt ture and to cool the said residual mixture to the extent desired. i

32. The method of conducting combustirm which comprises, maintaining a body of fuel in a furnace zone in. such manner that the said body of fuel will be free to move through the said zone under the influence of gravity as the fuel mass removed from the bottom of said zone. removing mate iai from the bottom of said body of fuel and charging fresh body of fuel, tunint ing; combustii'in in the middle portion or :illlll body of fuel by sup" plying air to said middle portion, the vol-- uiiie of said air being so correlated to the rate of movement of said fuel body that suliicient unburned but carbonized fuel will remain in the material in the lower part of. said fuel body to keep the said lower part in a condition permitting easy penetration of said lower part by the draft currenh anal contacting with the residual mixture of cart-onizod fuel and ash that has passed through the said middle portion of said body of fuel u stream of initially cool noueombustionaiupporting gas. the volume of the said gas relative to the volume of the said residual mixture being that required to cool the said residual mixture to the lie sired extent.

33 T he method of conducting combustion which comprises, advancing a body of fuel slowly through a combustion noncof a furnace chamber. the rate of advan e of said body of fuel being regulated to the which will carry through the said couii n.- tion zone a sufficient 'quantity of unburned but carbonized fuel to ,maintain the s id body of fuel easily permeable to the draft current supplied to said furnace and to establish a mixture of unburned fuel and ash in said fuel body beyond said combustion zone, introducing a regulated volume of air into said combustion zone to maintain combustion therein, quenchingthe said mixture of unburned fuel and ash in the said portion of said fuel body beyond said combustion zone. withdrawing the said quenched mixture of unburned fuel and ash from said furnace. separating the relative coarse portion of said mixture of quenched unburned fuel and fuel onto the t0! (if said ash comprising chiefly quenched unburned fuel from the relatively fine portion of the same comprising chiefly the ash of the burned fuel, mixing a regulated proportion of fresh fuel with the separated unburned carbonized fuel and feeding the resulting mixture to the portion of said fuel body advancing toward the combustion zone of said furnami 34. "The method of conducting combus tion which comprises, advancing a body of fuel slowly through a furnace chamber, the rate of said movement being that which will carry through a combustion zone of said furnace chamber a sufiicient quantity of unburned but carbonized fuel to maintain the body of fuel in said combustion zone in a condition affording a free passage to the draft current, introducing a regulated volume of a combustion-supporting draft current into said combustion zoneto maintain the combustion therein and conducting the gases of combustion to the place of use, cooling the mixture of carbonized fuel and ash that has been carried through the combustion zone of said furnace chamber by contacting therewith a stream of relatively cool gaseous fluid, the volume of said gaseous fluid relative to the volume of the said mixture of carbonized fuel and ash being that required to cool the said mixture to the degree desired, withdrawing the said fuel-ash mixture from said furnace chamber, separating the carbonized fuel of said mixture from the ash of the same, mixing a regulated proportion of fresh fuel with the said carbon-- ized fuel and feeding the resulting mixture onto the top of the body of fuel in said furnace.

35. The method of conducting combustion which comprises, advancing a body of fuel slowly through a furnace chamber, the rate of advance of said fuel relative to the volume of the draft current of said furnace being that which will carry through a combustion zone of said furnace chamber a sufficient quantity of unburned but carbonized fuel to maintain the body of fuel in said combustion zone in a condition affording a free passage to the draft current, introducing a regulated volume of combustion-supporting draft current into said combustion zone to maintain the combustion therein, conducting the major part of the gases produced by said combustion to the place of use, conducting the minor part of the said gases in contact with the up er portion, of the body of fuel in the said filrnace to preheat the same and to cool the said minor portion of the said gases, conducting the cooled gases to and contacting them with the mixture of carbonized fuel and ash that has been carried through the combustion zone of said furnace, the volume of the said minor stream of said gases being that re quired to cool the said mixture to the degree desired, conducting the said minor stream of said gases after the same has. been con tacted with the said mixture of carbonized fuel and ash back to the said combustion zone, withdrawing the cooled mixture of carbonized fuel and ash from the said furnace, mixing fresh fuel with the said carbonized fuel and feeding the said mixture onto the top of the said body of fuel in said furnace chamber.

36. The method of conducting combustion which comprises, advancing a body of fuel slowly through a furnace chamber, said movement being either intermittent or continuous, the rate of advance of said fuel body relative to the volume of the draft current of said furnace being that which will carry through a combustion zone of volume of combustion-supporting draft current into said combustion zone to maintain the combustion therein, conducting the major part of the gases produced by said combustionto the place of use, conducting the minor part of the said gases in contact with the upper portion of the body fuel in the said furnace to preheat the same and to cool the said minor portion of the said gases, conducting the cooled gases to and contacting them with the mixture of carbonized fuel and ash that has been carried through the combustion zone of said furnace, the volume of the said minor stream being tl at required to cool the said mixture to the degree desired, conducting the said minor stream after the same has been contacted with the said mixture of carbonized fuel and ash back to the said combustion zone, withdrawing the cooled mixture of fuel and ash from the said furnace, mixing fresh fuel with the said carbonized fuel and feeding the said mixture onto the top of the body of fuel in said furnace chamber, the proportion of the carbonized fuel in the said fuel mixture being that which is required to reduce the caking and clinkering of the fuel bed to the desired\degree.

37. The method of conducting combustion which comprises, maintaining a body of fuel in a furnace chamber in such manner that the said fuel will be free to move through the said chamber under the influence of gravity as the fuel mass is removed from ulriatji inn iv of v '1' Mn" mmwh mgr time? mm hm? 'f'slvmme": H

ER'QYURI; 1' the hwer u =-anl 1M3; of i a av rate i; mum in the said he; 55.:

the sa id comb 2 .s'; m

therein, conducting he major part of the gases produced by said oombustion to the place of use, conducting the minor part of the said gases in Contact with rho opp-:21 portion of the body of fuel in tlr. will furnace to preheat the same and to 0 al the said minor portion of iii-2 Said gases mndurling tho cooled gases to and oontartim diam itli the mixture o? oasl ml 'luel an the omnibus rm soul, of said formats, the volume of the said minor stream hair required to wool tho said mixture to the ocgroo ilsei-tirmi. L" ')!i(i ltl7i. 1hr said minor strvam al'ior i'ur min hrs iiotl roulartoil with the said mix are of oarhi ilZtHl fuel and ash lulvl'I to id ma' hmtion woe to rrjoin the main dzai'i it'uri'mit Withdrawing the cooled mixture of carbouhzud ash from the said uruarix mixing a 1 lated proportion of fresh fool with tho carbonized fool and feeding the said ture onto the top of tho said body of fuel i said fu nace ohamber.

42. The urethral of oomlucting rombustion Whirh comprisos, maintaining a hod}; of fuel in lur'naru rhauibar in such manner that the said fuel will bu free to move through the said rhaoiber under the influ ence of gravity as the i'ual mass is removed from the bottom of said l'urna o r-handmr. the said fuol uass at tho sauu} timo maintaining in the romhustion rvgiou of said furnace at free surfa u on its natural anglr of roposo, removing oitluu' vontinuously or intermittently rag-[dated portions of matrri-ii from tho bottom of tho said body of tool at a rate which will impart sulliciout movement to the said fuel body relativ lo the rate of fuel oomlu ion of said irrl in a combustion region oi tho said f lifin 'e to v-arrv ii-rough the said rombustion region a sullioiont quantity of unharmed but, rarl on1aal l'url to maintain the fuel body in said region in a c ndition asily pormoahlo to tho draft rurrori, introducing a rogulalied voluino of iomi'usiiousupporting dz". iflll'i'alll into said combos tiou region tr maintain tho combustion thoroin, conduriiug the maj r part f the, gases produced ii)" said oomhuslion to the place oi use, roudurtirg: tho minor part of tho said gases in oontari with tho uppor portion of the body of fool in ilu, said luruare to preheat the same and to cool the said minor portion of tho lll to the degree dosh-rd mnduciiug tho roohal gases to and contacting tllflll Willi the mixture of carbonized fuel and ash from the combustion region of said furnaui, tho volume of tho said minor stream bring that required to cool the said mixture to tho degree desired, conducting the said minor stream after the same has born contacted with the said mirctux-e hf carbonized fuel and ash back to said combustion region to rajoln tho main draft current, withdrawing no cooled mixtureof fuel and ash from the said Furnaoi, mixing a regulated proportion of fresh fuel with the said carbonized fuel and feeding the said iuifiuro onto the upper part of the said body of lc l in said furnace ihambor the prop: ti u of tho rai'houizwl fool in the said furl auxzturo iii-lug that which is requirf-d lo rodure ihc raking and olinhrring of the fresh fuel to the dvsirod drggjree. I

3. Thu method of roudurting the oombustiou of to l which romprirajs feeding tho said fuel in an inz'linod la; through a furnact chamber the angle of iuol' iatiou of said lapel being app. finiati-ly equal to or greater than the amrlr of ropose: of to said fuel. the matoriai disuhawing from the said layer being prrioittr-d to hank up {r in iho bottom of the said iuz'uao; uniil {no mawrial in said layer has a one-l its natural anglv of repose, aiainta niug a column of fuel hose has? is supporlvd by the upper portion oi tho said lzn'rr, imparting a rogulatr-d mowmout to th s fuel over said layer by witlulrawingawgulanal portions of the material thorein from tho bottom of the aid forum-e. the ratio oi suvh naivemeut boinn so regulated that there will always he a sufiicient proportion of mirbonizod fuel maintained in the fuel mass on the layer to prevent raking: and rliuheriug to the desired degree so aratirig the rarbonized fuel in the mixture of unburned c-arlmnizod fool and ash withdrawn from said ash pit, mixing a sullivieut porportion of fresh l'uul with the said rarbonized fuel to giro tho desired proportions of each in the fuel mixture and rhargiug the said mixturo outs the top of the said fuel column.

H. The method of mnduutl 9; the combustion of fuel whivh (:ompris feeding tho said furl in a u'aoparatinly thin inrlirard layer through a uruaco -hamlle'r, the anglr of inclination of said layer being approximately equal to \or groator than the angle of repose of the urid fur tho material dist-barging: from said'laysr liomg permitted to bank up from tho bottom of tho ash pit of said fur-nave until the matu'riul on the said layer llzla' asauiaotl its natural angle of repose, maintaining a column of fuel whose haso is supported by the upper portion of the said layrr. imparting a regulated movement to the Fuel over said layer by withdrawing regulated portions of the material therein from the. bottom of said furnace rhamhor. the rate of such. movement bring so regulated that there will always be a sufliciont proportion of carbonized fuel maintained on the said layer to prevent raking and rlinkering'to the desired degree, cooling the mixture of unburned hut carbonized fuel and ash disrhargcd from the. said layor by contacting;- tbr-rca'ith a stroam of a relativrly cool gaseous fluid, Withdrawing the said mixture from the said furnace 1% chmgmg bank up until the sunny} mg; by the 1.57m: gupumiug a wqui unignimi fuci 311mm mi mluum, whereby the said fuel prchmtmi and H10 $11M yortion 0f mauled, cumiuvtlng: the cooled the said uhmnucr MUM midi 133/61 said youhd gnsvs flwvin wixln mm gases to mrntacting the: the mixtme 0f nubzumd rm-hm and 'i'rw; ash :liwiuu w from was the vnlmew n1 (mr and mu regnlatu ta; gfmi a 1 hm; in mixtun; 0f mmnnuzed WE un the (kSiHl-f'; (in rm, uarriuvtiu; portion of the WM "umlmsxia phace of an ihdrim'lzxg in ure of mu" PEN-M1381. paw tile said mixt'." yum he mixing a sufiicent 3 portion a with th said carhnmzed 371103 to in desired priqiaorticms of Pfiih in the 5W mi); ture and charging the mid mixtur: mm: fizz! top of the said fuel (301111113.

Sigma at ".fnrk (zitg in Jew .1 ii Mum uf I 2 day m iii 

